Collection of Fecal Material of Fish for the Measurement of Digestibility

Collection of Fecal Material (using UA system) of Fish for the Measurement of Digestibility

Knowledge of apparent digestibility of feed ingredients for fish provides a rational basis for the formulation of diets. Digestibility estimations in fish depend on the collection of representative sample free of uneaten feed particles and the use of a digestions indicator (indirect methods). There are three methods/systems that have been adopted in several labortries around the world are most likely to produce meaningful estimates of digestibility of nutrients if used correctly (Bureau and Cho, 1999)

– the system of Ogino et al 1973) in which the feces are collected by passing effluent water from the fish tanks through a filtration column (TUF column

– Cho et al ., 1975 in which settling column is used to separate the feces from the effluent water (Guelph system) and

– Choubert et al., 1979 in which mechanically rotating the screen is used to filter out fecal material (St. Pee system)

Development of UA System:
Feedstuff digestibility assessment in fish is an essential prerequisite in determining the nutritionally adequate diets.

Unfortunately, the research on digestibility aspect in our culturable species (major carp) was never given due consideration.

The main barrier for conducting digestibility research was the lacking of facilities in term of fecal collecting system.

In view of importance of digestibility research for developing fish diet, a settling column system has recently been developed on the principle of Guelph system (Canada) by utilizing the local resources and designated the name as UA system.
This system consists of two parts: voiding tank and fecal settling column (figures 1 and 2).
Each voiding tank measure 60cm x 45cm and have a slop bottom, open into settling column (8cm diameter x 65cm high).
The upper part of settling column is connected with drainpipe, open into common drain system.
The velocity of the water flow is adjusted to minimize settling of the feces in the settling column.
Under normal operation, it has been observed that large feces particles are settled in the settling column within 2-4 minutes of being voided by the fish.

A series of eighteen tanks allow the determination of digestibility of eight ingredients (with two replications of each ingredients) and remaining two tanks being devoted to the reference diet (figures 3 and 4).
With the development of UA system, the research on digestibility has now become possible. Presently, two students of Ph.D are conducting research on apparent digestibility coefficient (ADC) of different ingredients in fish (major carps) by using newly developed UA system.